A light emitting element utilizing an electroluminescence (EL) phenomenon, when containing an appropriately selected light emitting material or when having an appropriately selected structure, emits light of various colors in a visible light region in addition to white color. Therefore, display devices and illumination devices using such a light emitting element have been actively developed.
Examples of light emitting elements utilizing the EL phenomenon include organic, inorganic and organic-inorganic hybrid light emitting diodes (LEDs). In a display device, a light emitting diode emits light when, for example, an electric current is supplied to a light emitting layer that is provided between a positive electrode provided for each of pixels located in a matrix and a negative electrode commonly provided for the pixels. Light is extracted through the negative electrode, which is transparent, and an image is displayed by light having a luminance and a chromaticity corresponding to each of the pixels. Display devices including such a light emitting diode are available in, for example, a type using a white light emitting layer and a color filter, and a type using a light emitting layer corresponding to each of the RGB colors and provided for each of pixels. The white light emitting layer may be formed by a general known method called a “tandem method”, by which a plurality of light emitting layers are stacked.
As a light emitting material for a light emitting diode in a display device, various types of materials using quantum dots (QDs) have been proposed. A quantum dot is a nanometer-order semiconductor particulate. The quantum dot can have light emission thereof controlled by an external energy. Conventionally proposed display devices include, for example, a display device using an inorganic light emitting diode including an inorganic light emitting layer containing quantum dots (see, for example, Japanese PCT National-Phase Laid-Open Patent Publication No. 2010-520603), a display device including a light scattering layer containing quantum dots provided on a negative electrode of a light emitting diode (see, for example, Japanese Patent No. 5243534), and the like.
However, most of the above-described conventional display devices have a stacking structure in which light emitting layers or light scattering layers both containing quantum dots are stacked in a vertical direction, in which light is extracted. When such a display device is applied to a high-definition compact panel including minute pixels, a problem may possibly occur that light leaks to adjacent pixels to cause mixture of display colors, and thus an image cannot be displayed accurately.